Food Preservation Lab (Salt)

Bacteria Growth with Salt as a Preservative. Rachel Wilensky. Alex Helfand. This lab tests the effectiveness of different concentrations of NaCl in low-sodium chicken broth solution as an antimicrobial preservative. Osmosis allows for the NaCl to absorb water so that bacteria does not have a moist environment to grow in. This creates a hypertonic environment where there is more NaCl than water preventing the bacteria from growing. Agar plates were created, and swiped with the different solutions. Observations of each concentration are recorded throughout a period of five days. The results are then used to determine which concentration gradient is most effective. When this lab was completed the different NaCl concentrations were: .431M, .905M, 1.91M, and 4.28M as well as a control with no NaCl added. All of these amounts except 4.28M allowed bacteria growth. Through calculations and observations, the ability of different amounts of NaCl to impede on bacteria growth was determined. These processes may be applied when attempting to determine effective concentrations of preservative to use to prevent bacteria growth.

Keywords: Hypertonic; osmosis; bacteria growth; agar plates; hypertonic; hypotonic

Source Citation:
Potter, N., & Hotchkiss, J. (1998). Food Science.New York: Springer Science + Business Media. (p. 233)